Abstract
Abstract The effect of Sc addition on creep resistance properties in the Al-0.7Fe-0.2Sc and Al-0.7Fe alloy has been studied. The microstructures before and after creep of Al-0.7Fe and Al-0.7Fe-0.2Sc alloy were investigated by optical microscopy, electron probe micro-analysis and transmission electron microscopy. In creep tests, the steady state creep rates of Al-0.7Fe-0.2Sc alloy were much lower than that of Al-0.7Fe alloy at 90–150 °C/70 MPa, it indicates that Sc addition significantly affected the creep resistance in Al-0.7Fe alloy cables. According to EPMA data and the known formation enthalpies of Al 3 Fe and Al 3 Sc phases, both of them are thermally stable. Additionally, TEM imaging showed that Al 3 Fe phases non-uniformly pinned on the subgrain boundary, and the average size of Al 3 Fe phase is approximately 0.4 µm. The nanosized Al 3 Sc precipitates (25–40 nm) both pinned on subgrain boundary and dislocation, making the pinned dislocations and subgrain boundary difficult to shift. The Orowan stress increment of ∆ σ Or in crept Al-0.7Fe-0.2Sc alloy is 61.3 MPa, whereas the ∆ σ Or of crept Al-0.7Fe alloy is 30.1 MPa, indicating that Al-0.7Fe-0.2Sc alloy cables possess higher creep resistance than Al-0.7Fe alloy cables.
Published Version
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